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United States Patent |
6,185,792
|
Nelson
,   et al.
|
February 13, 2001
|
Bi-directional self-locking cable tie
Abstract
A one-piece bi-directional cable tie for bundling articles having a tail at
one end, a locking head at the other end and an elongate strap body
therebetween may feature one or more fixed locking teeth opposite a
deflectable locking pawl so as to provide ratcheting locking engagement
with the two major surfaces of its strap body. The fixed teeth may provide
symmetrical performance characteristics or may provide selectable
performance characteristics depending on the direction of strap body
insertion through the locking head. The locking head may facilitate
wedging the strap body against the deflectable pawl. The deflectable pawl
may include a chevron-shaped upper surface so as to provide an undercut
surface for improved engagement with the locking teeth of the strap body.
Inventors:
|
Nelson; Andrew (Memphis, TN);
Wells, Jr.; Peter M. (Reeds Spring, MO)
|
Assignee:
|
Thomas & Betts International, Inc. (Sparks, NV)
|
Appl. No.:
|
197831 |
Filed:
|
November 20, 1998 |
Current U.S. Class: |
24/16PB; 24/17AP; 24/30.5P |
Intern'l Class: |
B65D 063/00 |
Field of Search: |
24/16 PB,17 AP,30.5 P,17 A
248/74.3
|
References Cited
U.S. Patent Documents
3102311 | Sep., 1963 | Martin et al.
| |
3103666 | Sep., 1963 | Bone.
| |
3457598 | Jul., 1969 | Mariani.
| |
3537146 | Nov., 1970 | Caveney.
| |
3588962 | Jun., 1971 | Feldberg | 24/16.
|
3735448 | May., 1973 | Waddington | 24/16.
|
3949449 | Apr., 1976 | Caveney et al. | 24/16.
|
3952373 | Apr., 1976 | Noorily | 24/16.
|
3965538 | Jun., 1976 | Caveney et al. | 24/16.
|
3967345 | Jul., 1976 | Sumimoto.
| |
4245374 | Jan., 1981 | Suzuki | 24/16.
|
4417656 | Nov., 1983 | Kato.
| |
4456123 | Jun., 1984 | Russell.
| |
4631782 | Dec., 1986 | Gecs.
| |
4640319 | Feb., 1987 | Walker.
| |
4640320 | Feb., 1987 | Avison et al.
| |
4683920 | Aug., 1987 | Furutsu.
| |
4688302 | Aug., 1987 | Caveney et al. | 24/16.
|
4712677 | Dec., 1987 | Russell.
| |
5042535 | Aug., 1991 | Schlottke.
| |
5146654 | Sep., 1992 | Caveney et al. | 24/16.
|
5317787 | Jun., 1994 | Fortsch | 24/16.
|
5884367 | Mar., 1999 | Teagno et al.
| |
Foreign Patent Documents |
2139091 | Mar., 1972 | DE.
| |
0 469 908 | Feb., 1992 | EP.
| |
0 611 038 | Aug., 1994 | EP.
| |
2 082 115 | Dec., 1971 | FR.
| |
2 089 514 | Jan., 1972 | FR.
| |
2 302 435 | Sep., 1976 | FR.
| |
1383912 | Feb., 1975 | GB.
| |
WO 89/06328 | Jul., 1989 | WO.
| |
Primary Examiner: Sakran; Victor N.
Attorney, Agent or Firm: Hoffmann & Baron, LLP
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims priority to U.S. Provisional Patent
Application Ser. No. 60/066,123, filed Nov. 21, 1997 and to U.S.
Provisional Patent Application Ser. No. 60/077,514, filed Mar. 11, 1998.
Claims
What is claimed is:
1. An elongate bi-directional one-piece cable tie comprising:
a locking head at one end, a tail at the other end and an elongate strap
body therebetween;
said strap body having opposing first and second major surfaces including a
plurality of locking teeth formed on each said surface;
wherein said locking head includes
a perimetrical wall defining a first aperture, a second aperture, and an
elongate strap passageway extending therebetween in a direction
substantially perpendicular to said strap body;
a shoulder surface and a block surface opposing said shoulder surface
extending along said passageway, said shoulder surface providing a first
rotation stop adjacent said first aperture and a second rotation surface
adjacent said second aperture; and
a deflectable locking pawl extending into said passageway across from said
block surface, said locking pawl being substantially aligned with said
strap body and further being deflectable by said strap body upon insertion
of said strap body through said passageway in a first direction, said
locking pawl providing locking engagement with said strap body upon
attempted withdrawal of said strap body in a second direction opposite to
said first direction;
wherein said locking pawl further includes:
a locking portion having a first locking tooth facing said first aperture
and said passageway and a second locking tooth facing said second aperture
and said passageway;
an elongate pawl base including a first cantilever arm having a first free
end extending towards said first aperture and a second cantilever arm
having a second free end extending towards said second aperture;
said locking pawl being connected to said shoulder by a flexible hinge
defining the closed end of both a first notch bounded by said first
cantilever arm and said shoulder and opening towards said first aperture,
and a second notch bounded by said second cantilever arm and said shoulder
and opening towards said second aperture;
wherein insertion of said strap body through said first aperture into said
passageway past said locking pawl causes said locking pawl to translate
and rotate about said flexible hinge towards said second aperture so that
said second free end of said second cantilever arm engages said second
rotation stop of said shoulder to close said second notch, and wherein
attempted withdrawal of said strap body back through said passageway
causes said first locking tooth of said pawl to engage a locking tooth of
said strap body and counter-rotate said locking pawl about said hinge and
said second end of said second cantilever arm to thereby force said strap
body against said block surface of said head; and
wherein insertion of said strap body through said second aperture into said
passageway past said locking pawl causes said locking pawl to translate
and rotate about said flexible hinge towards said first aperture so that
said first free end of said first cantilever arm engages said first
rotation stop of said shoulder to close said first notch, and wherein
attempted withdrawal of said strap body back through said passageway
causes said second locking tooth of said pawl to engage a locking tooth of
said strap body and counter-rotate said locking pawl about said hinge and
said first free end of said first cantilever arm to thereby force said
strap body against said block surface of said head.
2. The cable tie of claim 1, wherein said block surface includes a first
fixed locking tooth formed to engage the locking teeth on the strap body.
3. The cable tie of claim 2, wherein said block surface includes a second
fixed locking tooth for engaging the locking teeth on the strap body.
4. The cable tie of claim 3 wherein said first and second locking teeth of
said locking pawl are dissimilarly sized and shaped so as to provide
distinct hoop strengths depending on the insertion direction of said strap
body.
5. The cable tie of claim 3 wherein said first and second fixed locking
teeth on said block surface provide engagement surfaces facing opposite
apertures of said head so that each fixed locking tooth resists withdrawal
of said strap body towards the other fixed locking tooth.
6. The cable tie of claim 1, wherein each of said first and second stop
surfaces are tapered to face towards said passageway and its respective
notch opening to thereby provide a ramp surface along which said pawl base
may slide towards said strap body upon attempted withdrawal of said strap
body.
7. The cable tie of claim 1, wherein said locking pawl provides a
chevron-shaped surface in undeflected facing opposition to said block
surface.
8. The cable tie of claim 7, wherein said chevron-shaped surface is formed
by said first and second locking teeth of said locking portion being
transversely-spaced with respect to each other across said passageway.
9. The cable tie of claim 8, wherein said locking portion includes a third
locking tooth having a similar size and shape as, and transversely spaced
across said second locking tooth from, said first locking tooth.
10. The cable tie of claim 1, wherein said locking teeth on said first
major surface of said strap body are longitudinally staggered with respect
to said locking teeth on said second major surface of said body.
Description
FIELD OF THE INVENTION
The present invention relates generally to a self-locking cable tie for
securing a plurality of wires or similar articles. More particularly, the
present invention relates to a bi-directional cable tie which allows strap
insertion though the head in either direction.
BACKGROUND OF THE INVENTION
The use of cable ties to bundle a plurality of wires or similar articles
has long been known. Basic cable tie construction includes an elongate
cable tie strap having a tail at one end and a head at the other end. The
head includes a central passage or aperture therethrough for accommodating
a tail in an insertable fashion. The head supports a locking device
adjacent the head aperture to securely lock the cable tie body within the
aperture of the head to provide securement of the cable tie about the
bundle of wires. In one type of cable tie construction, the locking device
is a flexibly supported integrally formed pawl having plastic teeth which
engage corresponding teeth on a cable tie body to provide locking
engagement therebetween. As is typical of most cable ties, the tail of the
cable tie is inserted into the head aperture uniquely in one direction.
However, the art has also seen the use of bi-directional, or
symmetrically-formed, cable ties which permit the cable tie tail to be
inserted through the aperture in the head in either direction.
One such bi-directional cable tie is shown and described in co-pending
commonly assigned U.S. application Ser. No. 08/689,466, filed Aug. 9,
1996, entitled "A Self-Locking Cable Tie Strap With Symmetrical
Structure", issued on Mar. 23,1999, as U.S. Pat. No. 5,884,367 which is
herein incorporated by reference for all purposes. The cable tie of such
construction may be particularly used with an automatic cable tie
installing device where a plurality of cable ties held together in a reel.
A cable tie from the reel may be fed from a dispenser to a cable tie
installing gun for installation about a plurality of wires. The
symmetrical construction of the cable tie permits the cable tie to be
easily dispensed and aligned within the installation gun. As may be
appreciated, in order to accommodate insertion of the cable tie tail from
either direction, the pawl or locking device of the symmetrical cable tie
must be sufficiently flexible to permit deflection in either direction.
Such flexibility assures that the cable tie tail may be easily inserted
through the aperture in the head in either direction.
While such flexible construction permits easy insertion, it has been found
that in certain circumstances such cable ties may not exhibit sufficiently
high resistance to withdrawal forces as may be required in certain
applications. Additionally, the art has uniformly provided bi-directional
cable ties having symmetrical withdrawal-resistance characteristics while
ignoring circumstances where it may be desirable to provide a
bi-directional cable tie exhibiting discretely selectable, or
non-symmetrical, withdrawal-resistance characteristics depending upon
which direction the cable tie strap is inserted through the head.
Accordingly, it is desirable to provide a cable tie having a self-locking
feature in a symmetrical structure which exhibits ease of insertion of the
cable tie strap into the aperture in either direction and yet provides
suitably high resistance to withdrawal forces in order to maintain a
self-locking configuration. Additionally, it is desirable to provide a
self-locking feature in an asymmetrical structure which offers
discretely-selectable resistance to withdrawal forces according to the
direction of strap insertion.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a bi-directional cable tie for
bundling one or more articles.
It is another object of the invention to provide a bi-directional cable tie
having improved performance characteristics.
It is still another object of the invention to provide a bi-directional
cable tie having a fixed locking teeth capable of engaging the teeth on
the other side of the strap body as those engaging the locking pawl.
It is yet another object of the present invention to provide a
bi-directional cable tie providing asymmetric performance characteristics
in that the hoop strength depends on the direction through which the strap
body is inserted into the passageway.
It is even yet another object of the present invention to provide a
bi-directional cable tie with the locking teeth of the locking pawl
include an undercut strap engaging surface so as to increase the range of
pawl deflection providing locking engagement between the pawl and the
strap body.
In the efficient attainment of these and still other objects, the present
invention provides a bi-directional cable tie for bundling one or more
articles having a locking head at one end, a tail at the other end and an
elongate strap body therebetween. The strap body includes opposing first
and second major surfaces having a plurality of locking teeth formed on
each major surface. The locking head includes a first opening, a second
opening, and an elongate strap passageway extending therebetween in a
direction substantially perpendicular to the strap body. The head also
provides opposed shoulder and block surfaces extending along the
passageway. The shoulder surface provides a first rotation stop surface
adjacent the first opening and a second rotation stop surface adjacent the
second opening. A deflectable locking pawl extends from the shoulder
surface into the passageway across from the block surface. The locking
pawl is substantially aligned with the strap body and is deflectable by
the strap body upon insertion of the strap body in either direction
through the passageway. The locking pawl also provides locking engagement
with the strap body upon attempted withdrawal of the strap body in a
direction opposite to the insertion direction. The locking pawl includes a
locking portion having a first locking tooth facing both the first opening
and the passageway and a second locking tooth facing both the second
opening and the passageway, and an elongate pawl base including a first
cantilever arm having a first free end extending towards the first opening
and a second cantilever arm having a second free end extending towards the
second opening. The pawl base is connected to the shoulder by a flexible
hinge which defines the closed end of both a first notch bounded by the
first cantilever arm and the first stop surface and opening towards the
first opening of the head, and a second notch bounded by the second
cantilever arm and the second stop surface and opening towards the second
opening of the head. When the strap body is inserted through one end of
the passageway it contacts the near locking tooth of the locking pawl and
causes the locking pawl to translate and rotate about the flexible hinge
towards the opposite end of the passageway so that the free end of the
oppositely-extending cantilever arm engages its opposing rotation stop so
as to close the notch opening towards the exit end of the passageway.
Attempted withdrawal of the strap body back through the passageway causes
the contacted locking tooth of the pawl to engage a locking tooth of the
strap body and counter-rotate the locking pawl about the hinge to thereby
force the strap body against the block surface of the head; and
The present invention also contemplates increasing the hoop strength of the
cable tie of the present invention by providing one or more fixed locking
teeth on the block surface of the cable tie head for engaging the locking
teeth on the opposite surface of the strap as those engaging the
deflectable pawl. In one embodiment of the present invention a fixed
locking tooth is provided adjacent each opening so as to engage the strap
upon withdrawal back through the adjacent opening. The fixed locking teeth
are symmetrically provided so as to offer substantially the same
performance characteristic regardless of the insertion direction of the
strap body through the passageway in the head.
In another embodiment of the present invention a fixed locking tooth is
provided to effectively resist withdrawal through in only one direction.
This asymmetric bi-directional cable tie therefore offers a
discretely-selectable performance characteristics depending upon the
direction in which the strap body is inserted through the passageway. That
is, the hoop strength will be higher when the strap body is inserted into
the passageway in the direction that provides locking engagement between
the fixed tooth and the strap body than when inserted through the
passageway in the other direction.
In yet another embodiment of present invention the first and second
rotation stop surfaces of the shoulder are formed having a pronounced
taper so as to face both the adjacent opening in the cable tie head and
the passageway. The tapered stop surfaces provide a wedge surface enabling
the opposed cantilever arm to slide towards the hinge to thereby further
pin the strap body against the block surface of the head.
In even still another embodiment of the present invention, the locking pawl
provides a chevron-shaped upper surface in facing opposition to the block
surface so that the first and second locking teeth of the pawl provide
improved locking engagement with the teeth of the strap body. The
chevron-shaped upper surface is desirably formed by the side-by-side
formation of a pair of locking teeth having a first surface facing the
closest opening in the head and a second surface facing both the
passageway and the other opening of the head.
The present invention will be more readily appreciated in a reading of the
"Detailed Description of the Invention" with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a top elevational view of a cable tie of the present
invention.
FIG. 2 shows a side elevational view of the cable tie of FIG. 1.
FIG. 3 shows a longitudinal cross-sectional view of the cable tie of FIG. 1
taken through the line 3--3.
FIG. 4 is a cross-sectional view detailing the deflectable pawl of the
cable tie of FIG. 1.
FIG. 5 is a partial cut-away view of the cable tie of FIG. 1 in an
assembled configuration.
FIG. 6 is a top elevational view of an alternate embodiment of the cable
tie of the present invention.
FIG. 7 is a longitudinal cross-sectional view of the cable tie of FIG. 6.
FIG. 8 is a cross-sectional view detailing the deflectable pawl of the
cable tie of FIG. 6.
FIG. 9 is a partial cut-away view of the cable tie of FIG. 6 in an
assembled configuration.
FIG. 10 is a partial cut-away view of an alternate embodiment of the cable
tie of FIG. 6 in which the head include a single fixed locking tooth in
facing opposition to the pawl.
FIG. 11 is a front elevational view of an alternate embodiment of the cable
tie head and deflectable pawl of the cable tie of the present invention.
FIG. 12 is a cross-sectional view of the cable tie head and deflectable
pawl taken through the line 12--12 in FIG. 11.
FIG. 13 is a cross-sectional view of the passageway through the cable tie
head taken though the line 13--13 in FIG. 11.
FIG. 14 is a perspective cross-sectional view of the cable tie head taken
through line 14--14 in FIG. 11.
FIG. 15 is a cross-sectional view of the cable tie head of FIG. 11 in an
assembled configuration.
FIG. 16 is a cross-sectional view of still another embodiment of the cable
tie of the present invention providing undercut strap engaging surfaces on
the locking teeth of the deflectable pawl.
FIG. 17 is a cross-sectional view detailing the deflectable pawl of the
cable tie of FIG. 16.
FIG. 18 is a front elevational view of the locking pawl of the cable tie of
FIG. 16.
FIG. 19 is a perspective cross-sectional view of the head of the cable tie
of FIG. 16 detailing the locking teeth of the deflectable pawl.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1-3, a cable tie 10 of the present invention is shown.
Cable tie 10 is of the type referred to as a bi-directional cable tie.
Cable tie 10 is generally integrally formed of a suitable molded plastic
such as nylon.
Cable tie 10 includes an elongate cable tie strap body 12 terminating at
one end in a cable tie tail 14 at the other end and a cable tie head 16.
Cable tie strap body 12 is generally a planar member having a plurality of
notches or teeth 18 extending along each of opposed planar surfaces 18a
and 18b thereof. As will described in further detail hereinbelow, teeth 18
on each surface 18a and 18b are staggered with respect to one another.
Thus, the raised ridges 40 of teeth 18 on surface 18a are non-aligned with
the raised ridges of 40 of teeth 18 on surface 18b. By staggering the
teeth in such a manner, the respective depressions 42 between teeth are
not aligned. This avoids the cable tie strap body having a thinned or
narrowed cross-sectional thicknesses along the length thereof. Such a
construction improves the radial hoop strength of the cable tie in use and
reduces incidences of failure from breakage.
Cable tie head 16 defines a first aperture 17, a second aperture 19, and an
elongate passageway 20 extending therebetween for insertably accommodating
the cable tie tail 14 therethrough. As shown in FIG. 5, cable tie tail 14
is inserted generally in the direction of arrow A, however it may be
appreciated due to the symmetrical configuration of cable tie 10, cable
tie tail 14 may also be inserted in the direction opposite arrow A.
With additional reference to FIGS. 4 and 5, cable tie head 16 includes a
shoulder 25 and a block surface 21 extending along passageway 20 in facing
opposition. Head 16 further includes an integrally-formed pawl 22
extending into aperture 20. Pawl 22 is a symmetrical structure extending
from a central hinge 24 integrally formed with strap body 12. Pawl 22
includes a locking element 26 and an elongate pawl base 48 which are
symmetrically constructed having a pair of pawl teeth 50, 52 and
cantilever arms 54, 56 on each side thereof. First pawl tooth 50 includes
first and second pawl tooth surfaces 50a, 50b facing first aperture 17 and
block surface 21, respectively. Similarly, second pawl tooth 52 includes
first and second pawl tooth surfaces 52a, 52b facing second aperture 19
and block surface 21, respectively. Cantilever arm 54 extends towards
first aperture 17 and terminates at a first free end 54a. Cantilever arm
56 extends towards second aperture 19 and terminates at a second free end
56a.
Hinge 24 is positioned on and extends from a shoulder 25 of strap body 12.
Hinge 24 defines the closed ends of a first notch 60, opening towards
first aperture 17, and a second notch 62, opening towards second aperture
19. Shoulder 25 forms a first rotation-stop surface 25a across first notch
60 from cantilever arm 54 and a second rotation-stop surface 25b across
second notch 62 from second cantilever arm 56. Stop surfaces 25a and 25b
limit the rotation of pawl 22 due to strap insertion through passageway
20, thereby maintaining pawl 22 in ratchet engagement with strap body
teeth 18. Cantilever arms 54, 56 are designed so that upon rotation of
locking element 26, the free end 54a, 56a of the arm 54, 56 not engaging
the strap body 12 extends over and against its underlying rotation stop
surface 25a, 25b to thereby close its respective notch 60,62. Such
construction permits the strap body 12 to be easily inserted through
aperture 20.
For example, upon insertion of cable tie tail 14 into aperture 17, pawl
tooth 50 and cantilever arm 54 engage strap body teeth 18 on one planar
surface 18a of strap body 12. Locking element 26 is deflectable about
hinge 24 to permit continued insertion of strap body 12 through passageway
20. Pawl tooth 50 and cantilever arm 54 are each engageable with strap
body teeth 18 on surface 18a so as to provide ratcheting interlocking
engagement therewith. Such ratcheting interlocking engagement permits the
strap to be continually inserted in the direction of arrow A yet prevents
withdrawal of strap body 12 from head 16 in the direction opposite arrow
A. Upon attempted withdrawal, pawl tooth 50 and cantilever arm 54 urge
strap body 12 against upper wall 21 due to the counter rotation and
translation of pawl 22 about and across hinge 24 and stop surface 25b.
A further improvement in the cable tie of the present invention is shown in
FIGS. 4 and 5. Cable tie 10 further includes a modification to the upper
wall 21. In the present illustrative embodiment upper wall 21 includes
inwardly tapered entry surfaces 31 adjacent apertures 17 and 19 of head
16. Tapered surfaces 31 facilitate ease of insertion of cable tie tail 14
into passageway 20. Furthermore, upper wall 21 includes a centrally
disposed inwardly directed wall portion 32 extending towards pawl 22. Wall
portion 32 is an elongate member which projects downwardly from wall 21 to
reduce the opening within passageway 20. This assures engagement between
ratchet teeth 18 of strap body 12 and locking element 26 upon insertion of
strap body 12 into passageway 20.
In addition, wall portion 32 further includes at each end thereof, a
tapered projection 35 which extends further downwardly into passageway 20.
Projections 35 straddle each side of pawl 22. Upon insertion of strap body
12 into passageway 20, the teeth 18 on surface 18a are engageable with the
projection 35a positioned adjacent the exit end of passageway 20.
Deflection of pawl 22 permits continued insertion of strap body 12 in the
direction of arrow A. Upon an attempt to withdraw strap body 12 in a
direction opposite arrow A, teeth 18 on surface 18a become interlocked
with projection 35a further preventing withdrawal of strap body 12 from
passageway 20. As may be appreciated, projection 35b operates in the same
manner when tail 14 is inserted into passageway 20 in a direction opposite
arrow A.
Such construction of head 16 as is shown herein results in a cable tie 10
being resistant to higher withdrawal forces without significantly
increasing the force required to insert the tail into passageway 20.
Referring now to FIGS. 6-9, cable tie 110, an alternate embodiment of the
present invention, is shown. Similar numbering relates to similar
components previously described. Cable tie 110 is a bi-directional cable
tie having improved features which provide for enhanced resistance to
withdrawal forces in one direction. The operation of pawl 122 and its
locking engagement with strap body 112 is generally as previously
described. Cable tie 110 is generally integrally formed of a suitable
molded plastic such as nylon. Cable tie 110 includes an elongate cable tie
strap body 112 including at one end a cable tie tail 114 and at the other
end at a cable tie head 116.
Cable tie 110 includes an elongate cable tie strap body 112 terminating at
one end in a cable tie tail 114 at the other end and a cable tie head 116.
Cable tie strap body 112 is generally planar having a plurality of notches
or teeth 118 extending in staggered relationship along each opposed planar
surface 118a and 118b thereof. Cable tie head 116 defines a first aperture
117, a second aperture 119, and an elongate passageway 120 extending
therebetween for insertably accommodating the cable tie tail 114
therethrough. As shown in FIG. 9, cable tie tail 114 is inserted generally
in the direction of arrow A, however it may be appreciated due to the
symmetrical configuration of cable tie 110, cable tie tail 114 may also be
inserted in the direction opposite arrow A.
With additional reference to FIGS. 7 and 8, cable tie head 116 includes a
shoulder 125 and a block surface 121 extending along passageway 120 in
facing opposition. Head 116 further includes an integrally-formed pawl 122
extending into passageway 120. Pawl 122 is a symmetrical structure
extending from a central hinge 124 integrally formed with strap body 112.
Pawl 122 includes a locking element 126 and an elongate pawl base 148
which are symmetrically constructed having a pair of pawl teeth 150, 152
and cantilever arms 154, 156 on each side thereof. First pawl tooth 150
includes first and second pawl tooth surfaces 150a, 150b facing first
aperture 117 and block surface 121, respectively. Similarly, second pawl
tooth 152 includes first and second pawl tooth surfaces 152a, 152b facing
second aperture 119 and block surface 121, respectively. While first and
second pawl teeth 150 and 152 are shown having a dissimilar size and
shape, it is contemplated that need they may similarly formed as shown for
cable tie 10. Cantilever arm 154 extends towards first aperture 117 and
terminates at a first free end 514a. Cantilever arm 156 extends towards
second aperture 119 and terminates at a second free end 156a.
Hinge 124 is positioned on and extends from a shoulder 125 of strap body
112. Hinge 124 defines the closed ends of a first notch 160, opening
towards first aperture 117, and a second notch 162, opening towards second
aperture 119. Shoulder 125 forms a first rotation-stop surface 125a across
first notch 160 from cantilever arm 154 and a second rotation-stop surface
125b across second notch 162 from second cantilever arm 156. Stop surfaces
125a and 125b limit the rotation of pawl 122 due to strap insertion
through passageway 120, thereby maintaining pawl 122 in ratchet engagement
with strap body teeth 118. Cantilever arms 154, 156 are designed so that
upon rotation of locking element 126, the free end 154a, 156a of the arm
154, 156 not engaging the strap body 112 extends over and against its
opposite rotation stop surface 125a, 125b to thereby close its respective
notch 160, 162. Such construction permits the strap body 112 to be easily
inserted through passageway 120.
In order to improve the locking capability of the cable tie of the present
invention and in order to enhance the prevention of withdrawal of the
strap body in a direction opposite the direction of insertion, the present
invention configures upper wall 121 as shown in FIGS. 6-9. Upper wall 121
includes a non-symmetrical surface 130 having a pair of generally ramped
or angled surfaces 131 and 133 which extend into passageway 120 and are
asymmetrical to one side of the aperture. The end of ramped surfaces 131
and 133 forms spaced apart ledges 132 and 134 which define locking notches
for engagement with the teeth of strap body 112.
As particularly shown in FIG. 9, strap body 112 may be inserted in the
direction of arrow A. The dual tapered or ramped configuration of surface
130 helps guide strap body 112 through passageway 120 in such a direction.
Upon such insertion of strap body 112 into passageway 120, pawl 122 is
deflected. Continued insertion of strap body 112 into passageway 120 is
permitted by the particular configuration of ramped surface 131. Upon an
attempt to withdraw strap body 112 from passageway 120 in a direction
opposite arrow A, locking element 126 engages strap body teeth 118 on
surface 118b in a manner described hereinabove. However, the particular
configuration of surface 130 further resists the withdrawal forces as
ledges 132 and 134 also engage successive ridges 140 of teeth 118 on the
opposed surface 118a of strap body 112. The distance which ledges 132 and
134 are spaced apart on surface 130 is approximately equivalent to the
pitch or spacing between teeth 118 on surface 118a of strap body 112. Such
dual locking capability on both sides of strap body 112 helps retain strap
112 in a locked configuration within passageway 120 against withdrawal
forces. Thus, the cable tie shown in FIG. 8 is particularly resistant to
withdrawal forces applied in a direction opposite arrow A of the insertion
direction.
However, it may be appreciated that while the particular construction shown
herein allows easy insertion of the strap body into passageway 120 in the
direction of arrow A and prevents withdrawal of the strap body in the
direction opposite arrow A due in part to the improved configuration of
surface 130, the cable tie shown herein may be used in conventional
symmetrical fashion, i.e., the cable tie may still be employed with the
insertion direction being the direction opposite arrow A and a withdrawal
direction being in the direction of arrow A. Thus, the present invention
while providing a symmetrical structure where the body may be locked in
the head aperture in either direction provides superior performance
characteristics when used in a manner shown in FIG. 9.
Referring to FIG. 10, cable tie 110' is shown. Cable tie 110' substantially
similar to cable tie 110 shown in FIG. 7 with each element being
substantially identical and operating in a substantially identical manner.
However, cable tie 110' includes a further embodiment of upper wall 121'
wherein surface 130' includes a single ramped surface 134' extending into
and towards one side of passageway 120'. The ramped surface 134' forms a
downwardly extending ledge 137' within passageway 120. Thus, upon an
attempt to withdraw strap body 112' from passageway 120' ledge 137'
engages one of the ridges 140' of teeth 118' on surface 118a' so as to
provide further redundant locking engagement therewith. As with the
embodiment described above, the present embodiment, enhances the
resistance to withdrawal forces of the cable tie where the strap body is
attempted to be withdrawn in a direction opposite arrow A. However, as
with the embodiment shown in FIG. 6, the cable tie 110' functions in a
symmetrical manner by allowing strap body 112 to be inserted in head
aperture in either direction.
Referring now to FIGS. 11-15, cable tie 210, a further embodiment of the
present invention, is shown. Similar numbering relates to similar
components previously described. Cable tie 210 is a bi-directional cable
tie having features which provide for enhanced resistance to withdrawal
forces by facilitating the pawl wedging the strap body against the block
surface. The operation of pawl 222 and its locking engagement with strap
body 212 is generally as previously described. Cable tie 210 is generally
integrally formed of a suitable molded plastic such as nylon.
Cable tie 210 includes an elongate cable tie strap body 212 terminating at
one end in a cable tie tail 214 at the other end and a cable tie head 216.
Cable tie strap body 212 is generally planar having a plurality of notches
or teeth 218 extending in staggered relationship along each opposed planar
surface 218a and 218b thereof. Cable tie head 216 defines a first aperture
217, a second aperture 219, and an elongate passageway 220 extending
therebetween for insertably accommodating the cable tie tail 214
therethrough. As shown in FIG. 15, cable tie tail 214 is inserted
generally in the direction of arrow A, however it may be appreciated due
to the symmetrical configuration of cable tie 210, cable tie tail 214 may
also be inserted in the direction opposite arrow A.
With additional reference to FIGS. 12 and 15, cable tie head 216 includes a
shoulder 225 and a block surface 221 extending along passageway 220 in
facing opposition. Head 216 further includes an integrally-formed pawl 222
extending into passageway 220. Pawl 222 is a symmetrical structure
extending from a central hinge 224 integrally formed with strap body 212.
Pawl 222 includes a locking element 226 and an elongate pawl base 248
which are symmetrically constructed having a pair of pawl teeth 250, 252
and cantilever arms 254, 256 on each side thereof. First pawl tooth 250
includes first and second pawl tooth surfaces 250a, 250b facing first
aperture 217 and block surface 221, respectively. Similarly, second pawl
tooth 252 includes first and second pawl tooth surfaces 252a, 252b facing
second aperture 219 and block surface 221, respectively. Cantilever arm
254 extends towards first aperture 217 and terminates at a first free end
254a. Cantilever arm 256 extends towards second aperture 219 and
terminates at a second free end 256a.
Hinge 224 is positioned on and extends from a shoulder 225 of strap body
212. Hinge 224 defines the closed ends of a first notch 260, opening
towards first aperture 217, and a second notch 262, opening towards second
aperture 219. Shoulder 225 forms a first rotation-stop surface 225a across
first notch 260 from cantilever arm 254 and a second rotation-stop surface
225b across second notch 262 from second cantilever arm 256. Stop surfaces
225a and 225b are formed having a pronounced taper so that stop surface
225a faces both first aperture 217 and block surface 221 while stop
surface 225b faces both second aperture 219 and block surface 221. Stop
surfaces 225a and 225b limit the rotation of pawl 222 due to strap
insertion and also provide a surface for facilitating the wedging of pawl
222 between shoulder 225 and strap body 212 so as to further compress
strap body 212 against block surface 221. Cantilever arms 254, 256 are
designed so that upon rotation of locking element 226, the free end 254a,
256a of the arm 254, 256 not engaging the strap body 212 extends over and
against its opposite rotation stop surface 225a, 225b to thereby close its
respective notch 260, 262. Upon the attempted withdrawal of strap body
212, pawl 222 is pulled along the stop surface of the closed notch towards
the strap body and thus enhances the resistance to strap withdrawal. The
resultant force F acting on pawl 222 is shown in FIG. 15 to be acting
generally along the engaged stop surface.
Referring now to FIGS. 16-19, cable tie 210', yet still another embodiment
of the present invention, is shown. Similar numbering relates to similar
components previously described. Cable tie 210' is a bi-directional cable
tie exhibiting enhanced resistance to withdrawal forces by providing an
undercut to the locking teeth on the pawl for engaging the locking teeth
of the strap body. The operation of pawl 222' and its locking engagement
with strap body 212' is generally as previously described. Cable tie 210'
is generally integrally formed of a suitable molded plastic such as nylon.
Locking pawl 222' of cable tie 210' provides a chevron-shaped top surface
270' in undeflected facing opposition to blocking surface 221'. The
chevron-shape of top surface 270' provides an undercut to the tooth
engaging surfaces 250b' and 252b' of locking teeth 250' and 252',
respectively, for increasing the locking effectiveness of locking pawl
222'. In this embodiment, tooth engaging surfaces 250b' and 252b' face
both blocking surface 221' and apertures 217' and 219', respectively. The
chevron-shape of top surface 270' is desirably formed by
transversely-spacing locking teeth 250 and 252 across passageway 220' as
shown in FIGS. 16-19 so that the tooth engaging surfaces 250b' and 252b'
have uninhibited exposure to apertures 217' and 219', respectively.
Furthermore, the present invention contemplates providing a third locking
tooth 258' having a similar size, shape, and orientation as locking tooth
250' for providing transversely-uniform resistance forces against strap
body 212'. Desirably, the transverse dimension of locking teeth 250' and
258' are about the same as that of locking tooth 252'.
While the preferred embodiment of the present invention has been shown and
described, it will be obvious in the art that changes and modifications
may be made without departing from the teachings of the invention. The
matter set forth in the foregoing description and accompanying drawings is
offered by way of illustration only and not as a limitation. The actual
scope of the invention is intended to be defined in the following claims
when viewed in their proper perspective based on the prior art.
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